A spiropyran compound can be mentioned as a typical photochromic compound, and many photochromic spiropyran compounds are known [G. H. Brown, "Photochromism", Wiley Interscience, New York (1971)].
Spiropyran compounds, however, have a problem of poor fatigue resistance at the repetition of coloration and decoloration.
A spiro-oxazine compound is known as a photochromic compound having an improved fatigue resistance. For example, Japanese Unexamined Patent Publication No. 62-205185 discloses the following compound: ##STR2##
However, In the conventional spiro-oxazine compounds, however, the hue of the chromophoric seed is limited to violet-to-blue, and thus they have a low selection of hues.